Low-Level API

Use the low-level API when you need to add constraints to a verifier circuit or control its construction and execution. The unified API handles the usual recursion flow; prepared owners retain the circuit and prover setup for repeated proving.

Build a verifier circuit

The expert entry points are verify_p3_uni_proof_circuit and verify_batch_circuit. Their target, config, and lookup parameters depend on the native PCS. The FriRecursionBackend implementation is the checked reference for allocating targets, enabling the permutation tables, and building a FRI verifier circuit. Keep the circuit's permutation and FRI parameters aligned with the native proof's suite.

Supply opening witnesses

A FRI proof carries pruned multiproofs; the MMCS circuit needs a path for each query. Replay the opening transcript and call restore_fri_query_paths before set_fri_mmcs_private_data. The built-in config implementation shows the current set_fri_private_data(config, runner, op_ids, opening_proof, transcript) contract and the required opened-value observation. A hiding PCS also needs its random openings merged into the transcript at the same point as native verification.

Prove and verify the circuit

BatchStarkProver::prepare_circuit finalizes the relation and preprocessing once, then returns a PreparedCircuitProver. Feed runner traces to prepared.prove(&traces) and verify with the independently retained prepared.verifier() and a caller-supplied expected statement. The executable BabyBear example uses this path, including a public statement export.

For ordinary repeated recursion, PreparedLayer and PreparedAggregation also check the native input's shape before reuse. TrustedPreparedLayer and TrustedPreparedAggregation retain child authority and check statements as described in the API guide.